C++省略参数(va_list va_start va_arg va_end)的简单应用

原文参考自:http://www.cnblogs.com/hanyonglu/archive/2011/05/07/2039916.html

#include <iostream>
#include <stdarg.h>
using namespace std;
#define COUNT 5

const char *data[COUNT] = 
{
    "hello",
    "world",
    "java",
    "C#",
    "Python"
};
void fun(int a,int b,...)
{
    cout<<"a="<<a<<endl;
    cout<<"b="<<b<<endl;
    va_list ap;
    va_start(ap,b);
    cout<<"defaut="<<va_arg(ap,char*)<<endl;
    va_end(ap);
}
void Dolog(const char *szFileName,const char *fmt,...)
{
    va_list ap;
    va_start(ap,fmt);
    FILE *fp = fopen(szFileName,"a+");
    if(NULL == fp)
    {
        return;
    }
    vfprintf(fp,fmt,ap);
    va_end(ap);
    fclose(fp);
}

int main()
{
    int a=1,b=2;
    char str[] = "Hello World";
    fun(a,b,str);
    for(int i=0;i<COUNT;i++)
    {
        Dolog("log.txt","%s\n",data[i]);
    }
    system("pause");
    return 0;
}

log.txt内容:

hello
world
java
C#
Python